Filtering on LiveData User List column no longer updates after filtering by `(empty)`

Original reproduced in Jetty/HSQLDB XWiki 17.10.4, also reproduced in XWiki 17.10.8.

Steps to reproduce:

1. Create custom AWM with one short text field and User list field
2. Create several records with a filled-in list of users (create another one in advance) and one empty record
3. Create livedata in any wiki page using below code

   ```
   {{velocity}}
   {{liveData
     showPageSizeDropdown="true"
     properties="doc.title, shortText1, user1"
     source="liveTable"
     sourceParameters="className=Test AWM.Code.Test AWMClass&translationPrefix=test awm.livetable."
     rowCount="15"
     maxPages="10"
     defaultOrder="asc"
   }}
   {
     "meta": {
       "propertyDescriptors": [
         {"id": "doc.title", "name": "Test AWM", "editable": false},
         {"id": "shortText1", "name": "ID Name", "editable": false},
         {"id": "user1", "name": "User List", "editable": false}
       ]
     }
   }
   {{/liveData}}
   {{/velocity}}
   ```
   

4. Filter LiveData table by 3rd column, selecting firstly username and obtaining entry, and then selecting (empty)) to find empty records result, and try again to filter to obtain another result.

Actual result

After selecting (empty), LiveData correctly displays entries where the User List property is not filled.
However, if the filter is then changed to another user value (e.g. Administrator or anotherUser), the displayed results do not update and continue showing the previous (empty) filter results.
Only a full page refresh restores correct filtering behavior.

Expected result

After changing the filter value in the LiveData User List column (including switching from (empty) to another user value), the LiveData results should refresh accordingly and display only the entries matching the currently selected filter value.